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I‐75 Modernization Project Adams Square and Bloomfield Orchards Retrofit Analysis
Construction of Segment One: Completed September 1, 2017
August 16, 2018
1
A traffic noise study for the 2016/2017 I‐75 Modernization Project for segment one has been completed, using the latest, required traffic noise computer modelling. The purpose of this analysis was to determine if the existing walls in front of the Adams Square and Bloomfield Orchards communities are still feasible and reasonable, per current federal and state criteria. The location of the communities is shown in Figure 1. Adams Square and Bloomfield Orchards have existing noise walls that were built in 2003 and 1991, respectively. Based on the FHWA‐HEP‐12‐051 guidance requirement, Consideration of Existing Noise Barrier in a Type I Noise Analysis, each existing wall location was analyzed for one or more replacement noise barrier design options in front of the communities at different locations, to maximize noise abatement. In the Adams Square area, the topography allows for three noise barrier options to be considered: Option 1 consisted of evaluating a taller replacement noise barrier just inside the right‐of‐way in the same general location of the present sound wall; Option 2 considered constructing a new wall adjacent to the highway shoulder; and Option 3 was a combination of Option 1 and 2. In the Bloomfield Orchard community two noise barrier design options were evaluated, consisting of a minimum and maximum barrier height scenario. Both noise barrier design options were developed at the existing wall location because it provides the best location to break the line‐of‐site between the roadway and the houses and thereby achieve potential maximum noise reduction. Segment One construction was completed in September 2017. This analysis reflects the constructed improvements. Computer models were run using future traffic projections for the year 2040, to calculate traffic noise levels utilizing the largest available traffic volumes, to predict the highest traffic noise levels for residential areas. This analysis was completed in accordance with the July 2011 revisions to 23 CFR 772 as implemented by the MDOT in their 2011 Highway Noise Analysis and Abatement Handbook (MDOT Noise Handbook). The analysis also followed the guidance of FHWA‐HEP‐12‐051, Consideration of Existing Noise Barrier in a Type I Noise Analysis as noted above. Any proposed noise barriers must meet FHWA and MDOT reasonableness and feasibleness criteria. Traffic noise measurements were taken in July 2018. These measurements were taken for two 15‐minute intervals at one location within Adams Square and one location within Bloomfield Orchards. A validation model was run using these measurements. It was found the traffic noise measurements validate the proposed model to predict future noise levels. The following list includes the reasonableness and feasibleness criteria which must be met, to qualify for noise abatement. Each noise barrier is analyzed in order by the criteria in steps 1 through 5 below. No options evaluated in this analysis met criteria 2, 3, or 4 of the reasonableness nor feasibleness criteria as shown in tables 1 and 2 below. Feasibility is abatement that:
1. can be built while addressing safety and constructability concerns
2. provides at least a design year traffic noise reduction of 5 dB(A) for 75% of impacted receivers Reasonableness is abatement in which:
3. at least a 7 dB(A) reduction for 50% or more of the benefitted units. A design year traffic noise reduction of 10
dB(A) for at least one benefitted unit is a design goal, but non‐achievement does not eliminate the noise barrier
4. construction cost ($45 per square foot for the single side face surface of barrier) divided by the number of benefiting units is equal to, or less than $46,967 (2018) per benefiting unit
5. majority of benefiting residents and property owners are in favor of the noise barrier
I‐75 Modernization Project Adams Square and Bloomfield Orchards Retrofit Analysis
Construction of Segment One: Completed September 1, 2017
August 16, 2018
2
The corresponding criteria numbers above are presented in the first column in Tables 1 and 2 below. It is important to note that noise barriers are analyzed only for houses that meet the definition of “impacted”. MDOT defines an impact as an exterior residential location that receives an average of 66 decibels or more based on the loudest hour of the day, which is defined as approaching or during rush hour. Conclusions
Adams Square The existing sound walls were constructed in 2003. The original analyses for these walls followed FHWA and MDOT noise abatement policy and guidance utilizing the Federal Highway Program Manual 7‐7‐3 and the MDOT’s Noise Abatement Policy of 1996. The existing sound walls met the required noise abatement criteria for federal funding at the time of construction.
Within the Adams Square study area, the findings show predicted noise exposure at or above the 66 dB(A) FHWA Noise Abatement Criteria (NAC) impact threshold at homes behind the existing wall. There were 34 single family homes modeled behind the existing Adams Square wall with impacts predicted at 25 of these properties under future 2040 Design Build peak hour traffic conditions. As illustrated in Figure 2, these 25 impacted properties extend throughout the Adams Square community. The abatement analysis considered three proposed noise barrier design options. Option 1 consisted of a taller replacement wall at the current
location. Option 2 considered a replacement wall at the shoulder and a third option consisting of a combination of Options 1 and 2. A summary of the noise abatement cost reasonableness is provided in the first three rows of Table 1 for each of the proposed noise barrier design options. Similarly, the first three
rows of
Table 2 provides a summary of the acoustic feasibility and reasonableness associated with each barrier design. The noise
abatement analysis findings indicate that only one receptor benefit was achieved under all three noise barrier design
options evaluated. Thus, each proposed noise barrier failed to achieve adequate acoustic feasibility and reasonableness
cost requirements by not attaining adequate noise reduction at enough benefiting dwellings to attain a unit cost below
MDOT’s $46,967 maximum allowable limit. Therefore, none of the new replacement noise barrier design options met the
required MDOT abatement criteria. Based on these findings, the existing Adams Square sound wall should remain
unaltered in its current location as depicted in Figure 2.
Bloomfield Orchards The existing sound wall was constructed in 1991. The original analysis for this wall followed FHWA and MDOT noise abatement policy and guidance utilizing the Federal Highway Program Manual 7‐7‐3 and the MDOT’s Noise Abatement Policy of 1976. The existing sound wall met the required noise abatement criteria for federal funding at the time of construction.
I‐75 Modernization Project Adams Square and Bloomfield Orchards Retrofit Analysis
Construction of Segment One: Completed September 1, 2017
August 16, 2018
3
Within the Bloomfield Orchard study area, there were a total of 117 receiver sites modeled. Of these modeled sites, a total of 34 receivers (33 single family and one multi‐family) comprising a total of 41
receptors that were found impacted under future 2040 Build Year traffic conditions. As illustrated in Figure 3, the 34 impacted receivers extend throughout the Bloomfield Orchard community, but are largely confined to first row properties closest to the existing wall. The abatement analysis considered two
proposed noise barrier design options at the same general location of the present existing sound wall. Option 1 consisted of a taller replacement noise barrier that was optimized to satisfy the 75% minimum 5 dB(A) noise reduction requirement for acoustic feasibility. Option 2 consisted of designing the noise barrier to provide the greatest noise reduction achievable by raising some barrier segment heights, capturing as many benefiting dwellings as possible and thus decreasing the unit cost per benefiting dwelling. In both
options, the current existing wall location offered the best l noise reduction location in breaking the line‐of‐site along the sound path between the roadway and the adjacent community. A summary of the noise abatement cost reasonableness is provided in the last two rows of Table 1. Similarly, the last two rows of
Table 2 provide a summary of the acoustic feasibility and reasonableness assessment. The Option 1 findings show that the
proposed minimum height needed to satisfy the 75% minimum noise reduction was estimated to be nearly $55,000 per
benefit with a total of 31 benefits identified. Under the Option 2 maximum noise reduction scenario, 40 receptor benefits
(nine additional) were identified, however, the additional height needed to achieve this additional noise reduction
resulted in a unit cost of $50,506 which is still above MDOT’s $46,967 cost reasonableness allow limit. Even though both
proposed abatement options satisfied MDOT’s acoustic effectiveness percentage requirements of 5 dB(A) and 7 dB (A)
noise reduction, both were estimated to exceed MDOT’s maximum allowable cost effectiveness limit of $46,967 per
benefit. Therefore, based on these findings, the existing Bloomfield Orchard sound wall should remain unaltered in its
current location as depicted in Figure 3.
Table 1 Noise Barrier Cost Reasonableness Analysis
CRITERIA NUMBER NOT
MET
NAME
LENGTH (FEET)
AVERAGE HEIGHT (FEET)
COST (2018)
BENIFITING RECEPTORS
COST PER BENEFITTING RECEPTORS
COST REASONABLENESS
(YES/NO)?
2,3,4 Adams Square
Option 1 1,642 26 $1,921,140 1 $1,921,140 No
2,3,4 Adams Square
Option 2 1,301 26 $1,522,170 1 $1,522,170 No
2,3,4 Adams Square
Option 3 1,588 26 $1,857,960 1 $1,857,960 No
I‐75 Modernization Project Adams Square and Bloomfield Orchards Retrofit Analysis
Construction of Segment One: Completed September 1, 2017
August 16, 2018
4
4 Bloomfield Orchard
Option 1 3,013 12.5 $1,694,813 31 $54,671 No
4 Bloomfield Orchard Option 2
3,013 14.9 $2,020,217 40 $50,505 No
Table 2 Acoustic Feasibility & Reasonableness Results 2040 Build Year Traffic Volumes
Criteria Numbers
Met or Not Met
Noise Sensitive
Area
Number of
Impacted Receptors
Impacts Receiving a 5 dB(A) Reduction
Percent of Impacts
Receiving a 5 dB(A)
Reduction
Acoustic Feasible Criteria
(Yes/No)?
Benefitters1 Receiving a
10 dB(A) Reduction
Benefiters Receiving a
7 dB(A) reduction
Percent of Benefiters
Receiving a 7 dB(A)
Reduction
Acoustic Effective Criteria
(Yes/No)?
Not Met 2,3 & 4
Adams Square Option 1
25 1 4% No 0 0 0% No
Not Met 2,3 & 4
Adams Square Option 2
25 1 4% No 0 0 0% No
Not Met 2,3 & 4
Adams Square Option 3
25 1 4% No 0 0 0 No
Not Met 4
Bloomfield Orchard Option 1
41 31 76% Yes 12 29 94% Yes
Not Met 4
Bloomfield Orchard Option 2
41 40 98% Yes 28 29 73% Yes
I‐75 Modernization Project Adams Square and Bloomfield Orchards Retrofit Analysis
Construction of Segment One: Completed September 1, 2017
August 16, 2018
5
Bloomfield Orchards
Adams Square
Figure 1
I‐75 Modernization Project Adams Square and Bloomfield Orchards Retrofit Analysis
Construction of Segment One: Completed September 1, 2017
August 16, 2018
6
Figure 2
Adams Square
I‐75 Modernization Project Adams Square and Bloomfield Orchards Retrofit Analysis
Construction of Segment One: Completed September 1, 2017
August 16, 2018
7
Figure 3
Bloomfield Orchards